I'm experimenting with stringing a 10-string guitar in theorbo tuning, at least the first ten strings of a theorbo.
The bass to treble tuning should be:
D E F G A d g b e a
Note that the third string is the highest pitch, and the first two strings are down an octave from where you might expect them - it's a re-entrant instrument.
I made a video with this tuning but DOWN a minor 3rd, and the sound is good, but too muddy. So, I cobbled together a set for the correct pitch (setting aside arguments over what actual pitch was in the early 17th century - some say it was higher, some lower).
Note that strings 3 to 6 - A d g b - can be taken from a regular 6-string set.
The problem pitches are the low G, F#, D, and the first two strings. The first string is an a, the same pitch as the note a at the second fret of a regular g string. The second string is an e, the same pitch as the second fret of a regular d string.
My cobbled-together set has given me the notion that this tuning really works well on the 10-string, and the repertoire sounds great on it. But I'm not satisfied with having the wrong tension of strings here and there. Any suggestions?
The following is a video from BEFORE I worked out the set at the correct pitch. Here it is a minor 3rd too low, but it will give you an idea of what I'm getting at.